Video synthesis device, video synthesis method and recording medium

ABSTRACT

A rear-facing camera captures a live-action video image while a front-facing camera captures an image of a distributor. The avatar controller controls an avatar based on the image of the distributor captured by the front-facing camera, and move the position of the avatar in the real space coordinate system according to the position of the video synthesis device in the real space coordinate system. A synthesizer arranges the avatar in a predetermined position of a real space coordinate system and synthesizes the avatar with the live-action video image.

TECHNICAL FIELD

The present disclosure relates to a technology of generating anaugmented reality video image.

BACKGROUND ART

There has been an increasing number of video distribution services thatallow individuals to distribute video images via networks, in recentyears. Among such video distribution services, there is known anapplication program that allows distribution of a video image with acomputer graphics character (CG character) in place of a user. There isalso a known technology of tracking a face in a selfie captured by asmartphone, and reflecting the facial expression of the user to a CGcharacter.

CITATION LIST Patent Documents

PATENT DOCUMENT1: Japanese Unexamined Patent Publication No. 2017-188787

SUMMARY OF THE INVENTION

By synthesizing the CG character to a selfie video image by using aface-tracking technology, the CG character reflecting the facialexpression of the user him/herself can be easily synthesized real timewith a live-action video image.

However, the captured live-action video image is only the landscapebehind the user. To synthesize a CG character that reflects the user'sfacial expression with an image of a landscape before the user's eyes asthe background, the user needs to capture an image of him/herself withthe intended landscape at the back of the user by using a selfie stick.

In view of the above circumstance, it is an object of the presentinvention to more easily generate a video image in which an expressivecomputer graphics character is synthesized.

A video synthesis device related to a first aspect of the presentembodiment is a video synthesis device configured to generate anaugmented reality video image in which an avatar is synthesized with alive-action video image, including: a first imaging unit configured tocapture a live-action video image; a second imaging unit configured tocapture an image of an operator; a position detector configured todetect a position and an orientation of the first imaging unit or thevideo synthesis device in a coordinate system corresponding to a realspace; a controller configured to control the avatar based on an imagecaptured by the second imaging unit and move a position of the avatar inthe coordinate system according to a movement of the first imaging unitor the video synthesis device; and a synthesizer configured to arrangethe avatar in a predetermined position of the coordinate system andsynthesize the avatar with the live-action video image captured by thefirst imaging unit.

A video synthesis method related to a second aspect of the presentembodiment is a video synthesis method for generating an augmentedreality video image in which an avatar is synthesized with a live-actionvideo image, including computer-executed steps of: detecting a positionand an orientation of a first imaging unit configured to capture thelive-action video image, in a coordinate system corresponding to a realspace; controlling the avatar based on an image captured by a secondimaging unit configured to capture an image of an operator; moving aposition of the avatar in the coordinate system according to a movementof the first imaging unit; and arranging the avatar in a predeterminedposition of the coordinate system and synthesizing the avatar with thelive-action video image captured by the first imaging unit.

A recording medium related to a third aspect of the present embodimentis a computer-readable recording medium, storing a program to cause aprocessor to execute the processes of: detecting a position and anorientation of a first imaging unit configured to capture thelive-action video image, in a coordinate system corresponding to a realspace; controlling the avatar based on an image captured by a secondimaging unit configured to capture an image of an operator; and moving aposition of the avatar in the coordinate system according to a movementof the first imaging unit; and arranging the avatar in a predeterminedposition of the coordinate system and synthesizing the avatar with thelive-action video image captured by the first imaging unit.

This embodiment allows easier generation of a video image in which anexpressive computer graphics character is synthesized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an overall configuration of a videodistribution system including a video synthesis device of an embodiment.

FIG. 2 is an explanatory diagram showing how a distributor distributesan AR video image.

FIG. 3 is a diagram showing an example of an AR video image when thecapturing direction is panned to the right.

FIG. 4 is a functional block diagram showing an exemplary configurationof the video synthesis device of this embodiment.

FIG. 5 is a flowchart showing a flow of an avatar initial arrangementprocess.

FIG. 6 is a diagram showing an example in which a floor portion issuperimposed and displayed on a captured video image.

FIG. 7 is a diagram showing an example in which an avatar is arranged onthe floor portion of FIG. 6.

FIG. 8 is a diagram showing an example which a capturing direction istilted upward from the state of FIG. 7.

FIG. 9 is a flowchart showing a flow of an AR video image generatingprocess.

FIG. 10 is a flowchart showing a process of controlling facialexpressions and postures of the avatar.

FIG. 11 is a diagram showing an example in which buttons are displayedon a touch panel.

FIG. 12 is a diagram showing an example in which the avatar is turnedaround to show its back while the distributor is moving.

DESCRIPTION OF EMBODIMENTS

The following describes embodiments with reference to attached drawings.

With reference to FIG. 1, the following describes an overallconfiguration of a video distribution system including a video synthesisdevice of the present embodiment. The video distribution system includesa video synthesis device 1 and a video distribution server 3.

The video synthesis device 1 synthesizes a 3-dimensional computergraphics character (avatar) with a live-action video captured by thevideo synthesis device 1 and generates an augmented reality video image(hereinafter, AR video image).

The video distribution server 3 receives the AR video image from thevideo synthesis device 1 and distributes the AR video image to viewerterminals 9. The video distribution server 3 may distribute in real timethe AR video image received (so-called live broadcasting), or store theAR video image and distribute to the AR video image upon request fromany of the viewer terminals 9.

The video distribution system may include an avatar management server 5and a comment management server 7.

The avatar management server 5 manages 3-dimensional data of avatars.The video synthesis device 1 may allow generation of a customized avatarby combining parts of the avatar provided from the avatar managementserver 5.

The comment management server 7 receives a comment on the AR video imagefrom the viewer terminal 9 and distributes the comment to the videosynthesis device 1 and other viewer terminals 9.

The video synthesis device 1, the video distribution server 3, theavatar management server 5, the comment management server 7, and theviewer terminals 9 are connected and in communication with one anothervia a network.

The following describes the AR video image generated by the videosynthesis device 1, with reference to FIG. 2 and FIG. 3.

The video synthesis device 1 includes a rear-facing camera and afront-facing camera whose respective capturing directions are oppositeto each other, a microphone, a touch panel, and various sensors todetect the current position (e.g., an acceleration sensor, a gyrosensor, and the like). A video synthesis device 1 may be a smartphone ora tablet PC having a rear-facing camera and a front-facing camera.

As illustrated in FIG. 2, a distributor 200 holds the video synthesisdevice 1 and capture, with the rear-facing camera, an image of thelandscape the distributor 200 sees while capturing an image of thedistributor 200 with the front-facing camera. The video synthesis device1 generates an AR video image by synthesizing an avatar 100 with thelive-action video captured by the rear-facing camera. The videosynthesis device 1 reflects the facial expression of the distributor 200captured by the front-facing camera on the facial expression of theavatar 100. For example, while the distributor 200 is talking, the videosynthesis device 1 tracks the face of the distributor 200 captured bythe front-facing camera, and moves the mouth of the avatar 100 inresponse to the mouth movement of the distributor 200. The videosynthesis device 1 may reflect the movement of the head of thedistributor 200 on the avatar 100, or the gesture of the distributor 200on the avatar 100. With this, the distributor 200 is able to control theavatar 100 while capturing the landscape before his/her eyes.

The video synthesis device 1 fixes the avatar 100 to a coordinate systemthat corresponds to the real space and synthesizes the avatar 100 withthe video image. As illustrated in FIG. 3, when the capturing directionof the rear-facing camera is panned rightward, the avatar 100 shirtsleftward in the video image along with the other objects in the realspace.

[Configuration of Video Synthesis Device]

The following describes an exemplary configuration of the videosynthesis device 1, with reference to FIG. 4. As shown in the figure,the video synthesis device 1 has a spatial measurement unit 11, aninitial arrangement unit 12, an avatar controller 13, a synthesizer 14,a position detector 15, a front-facing camera 16, a rear-facing camera17, an input unit 18, a display 19, a communication controller 20, and astorage 21. Each part of the video synthesis device 1 may be configuredby a computer including an arithmetic processing device, a storagedevice and the like, and processes of each part may be executed by aprogram. Such a program may be stored in the storage device of the videosynthesis device 1, or stored in a recording medium such as a magneticdisc, an optical disc, a semiconductor memory, and the like, or providedthrough a network. For example, an application program may be installedin a smartphone to function the smartphone as the video synthesis device1.

The spatial measurement unit 11 performs measurement to obtain3-dimensional spatial information of a real space for arranging thereinthe avatar, set a real space coordinate system corresponding to the realspace, and detects an area in which the avatar can be arranged(hereinafter, avatar-arrangeable area). For example, a video image ofthe real space is captured by the rear-facing camera 17, and the3-dimensional spatial information of the real space at the capturingsite can be obtained through a measurement using a marker-less ARtechnology with a monocular camera. The spatial measurement unit 11detects, as the avatar-arrangeable area, a flat portion such as a floorand the like in the 3-dimensional spatial information obtained by themeasurement. The position to be detected as the avatar-arrangeable areaby the spatial measurement unit 11 is not particularly limited as longas arranging of the avatar does not look unnatural, and may be an areasloped with respect to the ground or an area with an irregular shape.

If the video synthesis device 1 has a depth camera or a stereo camera,the spatial measurement unit 11 may obtain 3-dimensional spatialinformation from a measurement result of the depth camera or from astereo image. The spatial measurement unit 11 stores, in the storage 21,the 3-dimensional spatial information obtained through the measurement.

The initial arrangement unit 12 determines an initial position of theavatar so that the avatar is in the avatar-arrangeable area detected bythe spatial measurement unit 11. For example, an image in which a symbol(e.g., a frame indicating the range of the floor, and the like)indicating the avatar-arrangeable area is superimposed on the videoimage of the real space captured by the rear-facing camera 17, promptingthe distributor to designate the initial position of the avatar. Whenthe distributor taps a position within the avatar-arrangeable area, theinitial arrangement unit 12 calculates the coordinates of the tappedposition in the real space coordinate system, and determines theposition as the avatar initial position. The initial arrangement unit 12may arrange the avatar in any position within the avatar-arrangeablearea. When the distributor swings the video synthesis device 1, theposition of the avatar may be randomly changed.

The avatar controller 13 tracks the face of the distributor captured bythe front-facing camera 16, and reflects the facial expression of thedistributor on the facial expression of the avatar. The avatarcontroller 13 may control the avatar according to an operation input bythe distributor through a menu and the like. The avatar controller 13may control the posture and the position of the avatar based on themovement of the video synthesis device 1. For example, when thedistributor is moving forward while capturing the landscape, the avatarmay be controlled to walk forward.

The synthesizer 14 arranges the avatar in the real space coordinatesystem, and synthesizes the avatar with the video image captured by therear-facing camera 17 to generate an AR video image. The AR video imageis displayed on the display 19, and transmitted to the videodistribution server 3 through the communication controller 20. Thesynthesizer 14 may store the AR video image in the storage 21. It shouldbe noted that data required for rendering the avatar is received fromthe avatar management server 5 and stored in the storage 21. Avatar datastored in the storage 21 in advance may be used.

The position detector 15 detects the position and the orientation of thevideo synthesis device 1 in the real space coordinate system (also theposition and the orientation of the rear-facing camera 17). Thesynthesizer 14 renders the avatar based on the position and theorientation detected by the position detector 15.

The front-facing camera 16 captures an image of the distributor (who isalso an operator of the video synthesis device 1).

The rear-facing camera 17 captures an image of the landscape and anobject of capturing to be delivered in the form of AR video image.

The input unit 18 receives an operation through the touch panel of thevideo synthesis device 1.

The display 19 displays on the touch panel an AR video image in whichthe avatar is synthesized with the live-action video captured by therear-facing camera 17. Various buttons to operate the avatar may bedisplayed.

The communication controller 20 transmits the AR video image to thevideo distribution server 3.

[Initial Arrangement of Avatar]

The following describes an exemplary avatar initial arrangement process,with reference to FIG. 5.

The process shown in FIG. 5 is executed at a time of determining theposition of the avatar in the real space coordinate system, before thedistributor generates the AR video image.

The distributor starts the video synthesis device 1, and uses therear-facing camera 17 to capture the video image of a site for arrangingthe avatar, and obtains the 3-dimensional spatial information of thesite for arranging the avatar (step S11). Specifically, an applicationprogram is started to operate a smartphone as the video synthesis device1, and an image of a flat place for arranging the avatar is captured bythe rear-facing camera 17. The distributor captures the image of thearrangement place while slightly moving the video synthesis device 1.The 3-dimensional spatial information is obtained from the movement of acharacteristic point detected based on the movement of the videosynthesis device 1 and the captured video image, and theavatar-arrangeable area which allows arrangement of the avatar thereinis detected. In this case, a flat “floor” is detected as theavatar-arrangeable area.

When the spatial measurement unit 11 obtains the 3-dimensional spatialinformation and detects the floor, the display 19 superimposes anddisplays a shape indicating the floor on the video image captured by therear-facing camera 17 (step S12). For example, as illustrated in FIG. 6,a frame 110 indicating the floor position is superimposed and displayedon the video image captured by the rear-facing camera 17.

When the distributor taps on the frame 110, the avatar controller 13arranges the avatar 100 in the position tapped as shown in FIG. 7 (stepS13). The coordinates of the tapped position in the real spacecoordinate system is set as the coordinate of the avatar's standingposition. When another position in the frame 110 is tapped, the newlytapped position is set as the avatars standing position. Once thecoordinates of the avatar in the real space coordinate system aredetermined, the synthesizer 14 superimposes and displays the avatar inthe live-action video captured by using the rear-facing camera 17. Afterthat, the avatar is superimposed and displayed in the live-action video,as if the avatar actually exists in the real space. For example, whenthe capturing direction of the rear-facing camera 17 is tilted upwardfrom the state illustrated in FIG. 7, the standing position of theavatar 100 remains fixed in the real space, and the upper half of theavatar 100 is displayed as illustrated in FIG. 8. Also when thecapturing direction of the rear-facing camera 17 is panned leftward orrightward, the avatar 100 is superimposed and displayed in thelive-action video while the standing position of the avatar 100 is fixedin the real space.

While the avatar 100 is displayed, the standing position of the avatar100 may be adjustable by dragging the avatar 100. For example, when thedistributor taps the avatar 100 and moves his/her finger leftward orrightward along the screen, while the avatar 100 is displayed asillustrated in FIG. 8, the standing position of the avatar 100 is movedleftward or rightward, respectively. When the distributor moves his/herfinger upward or downward, the standing position of the avatar 100 ismoved away from or closer to the distributor. When the avatar 100 ismoved frontward, rearward, leftward, or rightward, the movement of theavatar 100 is stopped so as not to exceed the range recognized as thefloor.

The initial arrangement unit 12 may randomly determine the standingposition of the avatar when the distributor swings the video synthesisdevice 1. When the distributor tilts the video synthesis device 1, theinitial arrangement unit 12 may determine the standing position of theavatar according to the tilt of the video synthesis device 1. Forexample, when the distributor tilts rightward the video synthesis device1, the avatar 100 is moved rightward and tilting the video synthesisdevice 1 towards the distributor moves the avatar 100 towards thedistributor.

The standing position of the avatar may be adjusted based on the imageof the distributor captured by the front-facing camera 16. For example,when the distributor turns to the right, the standing position of theavatar moves rightward. When the distributor looks down, the standingposition of the avatar moves towards the distributor.

When the distributor determines the position of the avatar, the initialarrangement unit 12 determines the size and the orientation of theavatar according to an operation by the distributor (step S14). Forexample, when the distributor flicks the touch panel upward or downward,the size of the avatar is enlarged or shrunk. The distributor flickingthe touch panel leftward or rightward rotates the avatar. Thedistributor tapping the touch panel with two fingers resets the size andthe orientation of the avatar to the initial size and the orientation.

On the floor including the avatar standing position, an object such as atatami mattress, carpet, a stage may be arranged. In a case where apedestal with a height is arranged as an object under the feet of theavatar, the standing position of the avatar is elevated by the height ofthe pedestal.

The avatar may be freely movable within a predetermined range of thefloor portion, around the initial position of the avatar. For example,when the distributor is silent for a while, the avatar may be controlledso as to walk around within the predetermined range.

[Generating AR Video Image]

After the distributor finishes initial arrangement of the avatar, thevideo synthesis device 1 starts capturing the distributor with thefront-facing camera 16 and starts generating the AR video image.

An exemplary process of generating an AR video image is described belowwith reference to FIG. 9.

At the same time the rear-facing camera 17 captures the image of thelandscape (step S21), the front-facing camera 16 captures the image ofthe distributor (step S22). The microphone collects audio to accompanythe video image.

The position detector 15 detects the position and the orientation of thevideo synthesis device 1 (step S23).

The avatar controller 13 controls the facial expression and the postureof the avatar based on the video image of the distributor captured bythe front-facing camera 16 (step S24). Processes of the avatarcontroller 13 will be described later.

The synthesizer 14 synthesizes the avatar with the live-action videocaptured by the rear-facing camera 17 to generate an AR video image(step S25).

[Avatar Control]

The following describes, with reference to FIG. 10, a control process ofthe facial expression and the posture of the avatar by the avatarcontroller 13.

The avatar controller 13 determines whether or not the distributor ismoving (step S31). Whether or not the distributor is moving isdetermined based on a movement of the video synthesis device 1 detectedby the position detector 15.

If the distributor is moving (Yes in step S31), whether or not theavatar position is in a locked state is determined (step S32). Theavatar position being in the locked state herein means that the positionof the avatar in the real space coordinate system is not movable. Thestanding position of the avatar is not moved even when the distributormoves. On the other hand, when the avatar position is not in the lockedstate, the avatar is movable according to the movement of the videosynthesis device 1, while the positions of the video synthesis device 1and the avatar in the real space coordinate system is kept at apredetermined distance from each other. When the distributor (i.e., thevideo synthesis device 1) moves, the avatar controller 13 moves theposition of the avatar according to the movement of the distributor. Themovement of the avatar is described later.

By operating a position-lock button 130 displayed on the touch panel asshown in FIG. 11, the locked state of the avatar position is released.When the position-lock button 130 is operated while the position of theavatar is in the locked state, the locked state of the avatar positionis released. If the position-lock button 130 is operated while theposition of the avatar is not locked, the position of the avatar isbrought into the locked state.

If the distributor is not moving (NO in step S31), or if the position ofthe avatar is locked (YES in step S32), the avatar controller 13determines whether or not a facial expression button is operated (stepS33). In the present embodiment, the touch panel displays facialexpression buttons 120A, 120B, and 120C, as illustrated in FIG. 11. Thefacial expression buttons 120A, 120B, and 120C correspond to facialexpressions of smiling, crying, and anger, respectively.

If any of the facial expression buttons 120A, 120B, and 120C is operated(YES in step S33), the avatar controller 13 changes the facialexpression of the avatar according to which one of the facial expressionbuttons 120A, 120B, and 120C is operated (step S34). Emotions can bemore clearly expressed by preparing animations of exaggerated facialexpressions, and animating the avatar according to operation of thefacial expression buttons. It is possible to cause the avatar togesticulate in addition to changing of the facial expression on theavatar. For example, operating the facial expression button of cryingcauses the avatar to make a gesture of wiping tears by a hand.

The touch panel may also display a button to control the posture of theavatar (including the orientation of the avatar). For example, the touchpanel may display a button to cause the avatar to turn around, a buttonfor causing the avatar to turn its face or upper half of the body to theright or left, and the like. By operating any of these buttons, theavatar controller 13 changes the posture of the avatar according to thebutton operated.

The facial expression and the posture of the avatar may be controllablefrom a menu. For example, an edge of the touch panel is swiped to call amenu bar and an item corresponding to an intended facial expression andposture of the avatar is selected.

The avatar may be controllable by an image of a hand gesture captured bythe front-facing camera 16. In this ease, the avatar controller 13associates hand gestures with control details of the avatar (facialexpressions, postures, and the like), and when a specific hand gestureis detected from the video image captured by the front-facing camera 16,controls the avatar according to the detected hand gesture. For example,when the front-facing camera 16 captures an image of a gesture of makinga fist, the facial expression of the avatar is changed to “angry.”

Further, the avatar may be controllable by an image of text or a designcaptured by the front-facing camera 16. In this case, when a specifictext or design is detected from the video image captured by thefront-facing camera 16, the avatar controller 13 controls the avataraccording to the detected text and the like. For example, text of“Smile!” is written on a piece of paper, and capturing the image of thatpaper by the front-facing camera 16 causes the avatar to smile.

The avatar may be controllable by a movement of the video synthesisdevice 1. In this case, the avatar controller 13 associates a movementof the video synthesis device 1 with a control details of the avatar,and controls the avatar according to the movement of the video synthesisdevice 1 detected by the position detector 15. For example, tilting thevideo synthesis device 1 causes the avatar to bow. However, tilting thevideo synthesis device 1 also tilts the landscape captured by therear-facing camera 17. Therefore, one frame of the video image capturedimmediately before the detection of the tilt is used as a stillbackground image and the bowing avatar may be synthesized with the stillimage. The background image may be a video image of several secondsbefore the detection of the tilts, instead of the still image.

The avatar controller 13 may control the avatar based on informationfrom a sensor attached to the distributor, or control the avatar byusing an external input device such as a keyboard. In this case, thevideo synthesis device 1 performs wireless communications with thesensor or the input device.

If no facial expression buttons arc operated (Y ES in step S33), theavatar controller 13 tracks the face of the distributor captured by thefront-facing camera 16, and reflects the facial expression of thedistributor on the facial expression of the avatar (step S35). Byreflecting the facial expression of the distributor captured by thefront-facing camera 16 on the avatar, the avatar can be moreexpressively controlled without troubling the distributor.

The avatar controller 13 may cause the avatar to make a motion ofspeaking, change the facial expression or the posture, or turn around,based on the audio of the distributor collected by a microphone.

If the distributor is moving (YES in step S31), and if the position ofthe avatar is not in the locked state (NO in step S32), the avatarcontroller 13 orients the avatar 100 to the direction in which thedistributor moves (step S36), and moves the standing position of theavatar 100 in the traveling direction (step S37). Specifically, theavatar controller 13 moves the position of the avatar in such a mannerthat the distance between the position of the video synthesis device 1and the standing position of the avatar in the real space coordinatesystem is kept at a predetermined interval. The avatar controller 13moves the avatar away from the distributor when the distributor (videosynthesis device 1) advances, moves towards the distributor when thedistributor moves back, and stops the avatar when the distributor stops.It should be noted that step S33 to step S35 may be executedindependently of the movement of the avatar. Specifically, step S33 maybe executed after step S37 is executed.

The avatar controller 13 may lock the orientation of the avatar, ororient the avatar to the traveling direction. For example, when thedistributor moves forward in the state shown in FIG. 11, while theposition of the avatar is unlocked and the orientation of the avatar islocked, the avatar controller 13 causes the avatar to move backwardwhile orienting the avatar to face the video synthesis device 1. On theother hand, when the distributor moves forward in the state shown inFIG. 11, while neither the position nor the orientation of the avatar isunlocked, the avatar controller 13 orients the avatar in the travelingdirection and causes the avatar to move forward, as illustrated in FIG.12.

When the microphone collects a voice of someone other than thedistributor, the avatar controller 13 may orient the avatar to thesource of the audio.

When the avatar is moved to an object other than the floor (e.g., awall), the avatar controller 13 may stop the avatar at the end of thefloor without further moving the avatar. When the distributordistributes an AR video image while walking, the spatial measurementunit 11 detects a flat portion in the traveling direction from the videoimage captured by the rear-facing camera 17, and the avatar controller13 moves the avatar to the flat portion in the traveling direction. Asthus described above, when the distributor distributes an AR video imagewhile walking on a road, it is possible to generate an AR video image inwhich the avatar appears as if it is walking on the road.

When the distributor pans the rear-facing camera 17 to the left or rightwhile the avatar position is not in the locked state, the avatarcontroller 13 may move the avatar leftward or rightward, according tothe capturing direction.

As described hereinabove, in the present embodiment, a rear-facingcamera 17 captures a live-action video image while a front-facing camera16 captures an image of a distributor. An avatar controller 13 controlsan avatar based on an image of the distributor captured by thefront-facing camera 16. A synthesizer 14 arranges the avatar in apredetermined position of a real space coordinate system and synthesizesthe avatar with the live-action video image. This way, the distributoris able to generate an AR video image in which the avatar reflectingthereon a facial expression of the distributor is synthesized, whilecapturing a landscape before the eyes of the distributor. By trackingthe face of the distributor captured by the front-facing camera 16 andreflecting the facial expression on the avatar, an expressive avatar canbe synthesized.

In the present embodiment, a spatial measurement unit 11 obtains3-dimensional spatial information of a location where the live-actionvideo image is captured, and detects an avatar-arrangeable area whichallows arrangement of the avatar. The initial arrangement unit 12arranges the avatar in the avatar-arrangeable area and determines theposition of the avatar in the real space coordinate system. This way,the avatar can be fixed in the real space without setting a marker fordetermining a standing position of the avatar.

In the present embodiment, the avatar controller 13 moves the positionof the avatar in the real space coordinate system according to theposition of the video synthesis device 1 in the real space coordinatesystem. Therefore, when the distributor holds the video synthesis device1 and captures an image while walking, an AR video image in which theavatar moves along with the movement of the distributor is synthesizedcan be generated.

It should be noted that the present embodiment deals with a case wherethe video synthesis device 1 generates an AR video image. However, thevideo synthesis device 1 may transmit, to a server, necessaryinformation for generating an AR video image such as live-action videoimage captured by the rear-facing camera 17 and the image captured bythe front-facing camera 16, and the AR video image may be generated inthe server or in a cloud environment.

The present disclosure relates to the subject matter described inJapanese patent application No. 2018-225031 filed on Nov. 30, 2018, theentire contents of which are herein incorporated by reference.

1. A video synthesis device configured to generate an augmented realityvideo image in which an avatar is synthesized with a live-action videoimage, the device comprising: a first imaging unit configured to capturea live-action video image; a second imaging unit configured to capturean image of an operator; a position detector configured to detect aposition and an orientation of the first imaging unit or the videosynthesis device in a coordinate system corresponding to a real space; acontroller configured to control the avatar based on the image capturedby the second imaging unit and further configured to move a position ofthe avatar in the coordinate system according to a movement of theposition of the first imaging unit or the video synthesis device in thecoordinate system; and a synthesizer configured to arrange the avatar ina predetermined position of the coordinate system and further configuredto synthesize the avatar with the live-action video image captured bythe first imaging unit.
 2. The video synthesis device of claim 1,wherein the controller is configured to control the avatar based on agesture of the operator, text, or a design, the gesture of the operatorbeing captured by the second imaging unit.
 3. The video synthesis deviceof claim 1, wherein the controller is configured to control anorientation of the avatar based on the movement of the video synthesisdevice.
 4. The video synthesis device of claim 1, further comprising aninput unit through which an operation by the operator is input, whereinthe controller is configured to control the avatar based on theoperation input through the input unit.
 5. The video synthesis device ofclaim 1, further comprising a microphone through which audio is input,wherein the controller is configured to control the avatar based on theaudio input through the microphone.
 6. The video synthesis device ofclaim 1, wherein capturing directions of the first imaging unit and thesecond imaging unit are opposite to each other.
 7. A video synthesismethod for generating an augmented reality video image in which anavatar is synthesized with a live-action video image, the method,executed by a computer, comprising: detecting a position and anorientation of a first imaging unit configured to capture thelive-action video image, in a coordinate system corresponding to a realspace; controlling the avatar based on an image captured by a secondimaging unit configured to capture an image of an operator; moving aposition of the avatar in the coordinate system according to a movementof the position of the first imaging unit in the coordinate system; andarranging the avatar in a predetermined position of the coordinatesystem and synthesizing the avatar with the live-action video imagecaptured by the first imaging unit.
 8. A computer-readable recordingmedium, storing a video synthesis program for generating an augmentedreality video image in which an avatar is synthesized with a live-actionvideo image that causes a processor to execute: detecting a position andan orientation of a first imaging unit configured to capture thelive-action video image, in a coordinate system corresponding to a realspace; controlling the avatar based on an image captured by a secondimaging unit configured to capture the image of an operator; moving aposition of the avatar in the coordinate system according to a movementof the position of the first imaging unit in the coordinate system; andarranging the avatar in a predetermined position of the coordinatesystem and synthesizing the avatar with the live-action video imagecaptured by the first imaging unit.
 9. The video synthesis method ofclaim 7, wherein controlling the avatar is based on a gesture of theoperator, text, or a design, and wherein the gesture of the operator iscaptured by the second imaging unit.
 10. The video synthesis method ofclaim 7, further comprising: controlling an orientation of the avatarbased on the movement of the first imaging unit.
 11. The video synthesismethod of claim 7, further comprising: receiving an operation; andcontrolling the avatar based on the operation.
 12. The video synthesismethod of claim 7, further comprising: collecting audio by a microphone;and controlling the avatar based on the audio.
 13. The video synthesismethod of claim 7, wherein capturing directions of the first imagingunit and the second imaging unit are opposite to each other.
 14. Thevideo synthesis method of claim 7, wherein controlling the avatar isbased on a gesture of the operator, text, or a design, and wherein thegesture of the operator is captured by the second imaging unit.
 15. Thecomputer-readable recording medium of claim 8, further causes aprocessor to execute: controlling an orientation of the avatar based onthe movement of the first imaging unit.
 16. The computer-readablerecording medium of claim 8, further causes a processor to execute:receiving an operation; and controlling the avatar based on theoperation.
 17. The computer-readable recording medium of claim 8,further causes a processor to execute: collecting audio by a microphone;and controlling the avatar based on the audio.
 18. The computer-readablerecording medium of claim 8, wherein capturing directions of the firstimaging unit and the second imaging unit are opposite to each other. 19.The video synthesis device of claim 1, wherein the first imaging unit isa front-facing camera and the second imaging unit is a rear-facingcamera.
 20. The video synthesis device of claim 1, wherein the positiondetector includes one or more sensors.